Running GSIM CLAS simulation
- 1 GSIM Inventory
- 2 Running GSIM
- 2.1 Setting an Event Generator and create events file
- 2.2 Converting generated data files to GEANT-3 format input
- 2.3 Running generated events through a CLASS GEANT-3 simulation
- 2.4 Converting the GSIM output file to ROOT
- 2.5 Observing the output ROOT TTree
- GSIM directory is to be located on the farm, at a large enough work disk. An example of the simulation inventory can be found at
/work/halla/e07006/disk1/Erez/GSIM (will be used for the remainder of the documentation as $GSIM)
Setting an Event Generator and create events file
- PYTHIA is used as the base-line event generator (EG) for GSIM
- The existing EG is a fortran script located under $GSIM/Documents/ directory.
Setting Event Generator
- The EG should be modified for the specific solid target. An example for 12C can be found at
- To build the event generator use the build compilation command, e.g.
cd $GSIM/Documents/ build_EG_cs
(the result: an executable event generator e.g. EventGenerator_exe/EG_C.exe)
Generate the Events
- Generate the events by executing the EG, e.g.
./EG_C.exe > test.dat
(the result: a data file EventGenerator_exe/test.dat)
Look at the generated distributions
- A utility for observing the generated data exist in the main EG directory $GSIM/Documents/EventGenerator/LeptoRoot
- Port the data file into the utility directory
cp $GSIM/Documents/EventGenerator_exe/test.dat $GSIM/Documents/LeptoRoot/
- A perl script is used to write it in the right format
./leptoroot.pl < test.dat > data.dat
(the result: a different (just numbers) data file LeptoRoot/data.dat)
- An executable is then used to write the data into a ROOT TTree
(the result: a ROOT file LeptoRoot/data.root that will enable you to observe the generated distributions)
Converting generated data files to GEANT-3 format input
- port the generated-events data file (in this example test.dat) to the converters utility and convert it to txt format.
For example, a file from the 2H target would be converted by
cp $GSIM/Documents/EventGenerator_exe/test.dat $GSIM/converters ./convert_deut < test.dat > convert_output.dat
(the result: a txt file /converters/convert_output.dat )
- port and convert the txt file to a G3 part format corresponding to the MCTK bank (works better than particle bank in G3)
mv convert_output.dat ../Lepto64 cd ../Lepto64 ./txt2part -m -omctk.evt < convert_output.dat
(the result: a part file /Lepto64/mctk.evt suitable for GSIM)
Running generated events through a CLASS GEANT-3 simulation
running GSIM with the generated events
- port the events file to the shared directory
mv mctk.evt share cd share
- to run the first XXXX events through the simulation, modify the ffread file so that it triggers XXXX events
- then source the shell script that runs GSIM
(the result: 2 bos + 1 txt files , gsimtest.txt, gsimtest.bos, gpp_test.bos and the output file outfile1 )
- gsimtest.bos contains the data 'collected' by CLASS (ADC/TDC)
- gpp_test.bos incorporates preprocessing to add smearing of the data
- outfile1 is the physical data after REConstruction SYStem analyzed it
Look at the output files
- using COUNTBS one could count the number of events, e.g.
(Note the first additional two events are header and are not to be accounted)
- using BOSDUMP code, one can look at the data from the terminal, e.g.
./bosdump gsimtest.bos ./bosdump gpp_test.bos
Converting the GSIM output file to ROOT
- this is the easy part now. For an output file named outfile1 e.g., use
./WriteRootDst -o output.root -GSIM outfile1
(the result: a root file /output.root)
Observing the output ROOT TTree
- The ROOT TTree is called
- To look at the data use e.g.
CLASEVENT -> StartViewer()
- The 'collected data' is stored in EVNT.XXXX variables, while the generated data is stored in GSIM.XXXX variables.